The semiconductor industry, which has an annual turnover of over $300 billion, bases its growth on being able to fabricate computer chips with an ever-increasing number of transistors for greater computing power and power efficiency. This requires the precise manufacture of ever-smaller transistors, which now have dimensions in the nanoscale.
Conventional light-based fabrication methods rely on increasingly smaller wavelengths of light to manufacture devices; however, these methods are reaching their limits of effectiveness. One potential alternative is fabrication by self-assembly, whereby researchers harness the guiding physics of a system to build nanoscale objects. By modifying the chemical structure and properties of individual components, scientists are able to direct how the components fit together into well ordered patterns and effectively ‘direct’ the self-assembly process.
A team of researchers from The University of Queensland and Intel Corporation, led by Associate Professor Idriss Blakey, Associate Professor Kevin Jack and Professor Andrew Whittaker, have combined light-based techniques with self-assembly to print nanoscale features approximately 5 000 times narrower than the width of a human hair. Using these methods, they were able to overcome the limits of solely light-based techniques and take a step towards next generation transistors. The researchers synthesised polymer molecules with properties ideal for self-assembly. By directing the self-assembly of the polymers, the team was able to print features less than 10 nanometres in size, which is far smaller than those achieved through light-based patterning alone. In addition, they have patented a methodology for improving the precision of patterns generated by light-based lithography, which will improve the performance of next generation computer processes.
The project utilised a number of specialised characterisation tools at ANFF-Q for the synthesis of the polymers such as size exclusion chromatography (with multi-angle light scattering) and ellipsometry. The ANFF-Q reactive ion etching system was also used to study the etch resistance of the polymer systems and the atomic force microscopy was used for the characterisation of the surface of thin films and imaging of patterned features. Elliot Cheng, now a Professional Officer at ANFF-Q, was the Post-Doc that developed a CMOS compatible directed self-assembly process for this project. Support was provided by ANFF-Q Professional Officers Elena Taran and Kai-Yu Liu. The resulting fabrication process is directly compatible with semiconductor fabrication methods, yet has a much higher resolution than current light-based systems.
The outcomes of this project give Australia the chance to play a significant global role in developing processes for high end semiconductor manufacture. The project was undertaken with the support of the Intel Corporation and the Australian Research Council (ARC) linkage scheme. Further work is also being undertaken in conjunction with Dow Chemical Company under an ARC Linkage Project to investigate other ways polymers can be used to improve the manufacture of semiconductors.
Keen, I. et al. (2014). Behavior of Lamellar Forming Block Copolymers under Nanoconfinement: Implications for Topography Directed Self-Assembly of Sub-10 nm Structures. Macromolecules, 47, 276-283, DOI:10.1021/ma4019735.